Landmark reports from reputable sources have concluded that the United States wastes hundreds of billions of dollars every year on medical care that does not improve health outcomes. While there is widespread agreement over how wasteful medical care spending is defined, there is no consensus on its magnitude or categories. A shared understanding of the magnitude and components of the issue may aid in systematically reducing wasteful spending and creating opportunities for these funds to improve public health.To this end, we performed a review and crosswalk analysis of the literature to retrieve comprehensive estimates of wasteful medical care spending. We abstracted each source's definitions, categories of waste, and associated dollar amounts. We synthesized and reclassified waste into 6 categories: clinical inefficiencies, missed prevention opportunities, overuse, administrative waste, excessive prices, and fraud and abuse.Aggregate estimates of waste varied from $600 billion to more than $1.9 trillion per year, or roughly $1800 to $5700 per person per year. Wider recognition by public health stakeholders of the human and economic costs of medical waste has the potential to catalyze health system transformation.